The proposed research will investigate visual information processing in schizophrenia. A backward masking paradigm, the critical interstimulus interval, will be used to obtain information about three levels of information processing in schizophrenics: preattentive filtering, iconic storage, (Neisser, 1967) and speed of information transfer from iconic storage to the higher brain centers. Four groups, 10 inpatient chronic (process) paranoids, 10 inpatient chronic (process) nonparanoids, 10 matched nonschizophrenic psychiatric inpatients, and 10 college students will be studied. Criterion performance will consist of six consecutive correct identifications of a T or A in a two alternative forced choice recognition task. Both the minimum exposure duration for criterion performance, when no mask is present, and the minimum interval between the target stimulus (T or A) and mask for criterion performance will be determined for each subject four separate times in four separate sessions. Group differences in preattentive filtering will be inferred from a differential response to practice among the groups. Group differences in icon quality and/or icon formation, the second stage of information processing to be measured, will be inferred from group differences in the minimum stimulus duration for criterion performance. Group differences in information processing speed will be inferred from group differences in the critical interstimulus interval. This study will: (1) help determine whether or not schizophrenia involves a disorder in the early stages of information processing, and (2) demonstrate the potential utility of the masking procedure to provide an objective measure to distinguish schizophrenics or subgroups of schizophrenics from nonschizophrenics.